How to specify multiple conditions in an if statement in javascript

Here is how I mention two conditions if this or this

if (Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '') PageCount= document.getElementById('<%=hfPageCount.ClientID %>').value; } 

10 Answers

just add them within the main bracket of the if statement like

if ((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) { PageCount= document.getElementById('<%=hfPageCount.ClientID %>').value; } 

Logically this can be rewritten in a better way too! This has exactly the same meaning

if (Type == 2 && (PageCount == 0 || PageCount == '')) { 

Here is an alternative way to do that.

const conditionsArray = [ condition1, condition2, condition3, ] if (conditionsArray.indexOf(false) === -1) { "do somthing" } 

Or ES7+

if (!conditionsArray.includes(false)) { "do somthing" } 

I am currently checking a large number of conditions, which becomes unwieldy using the if statement method beyond say 4 conditions. Just to share a clean looking alternative for future viewers... which scales nicely, I use:

var a = 0; var b = 0; a += ("condition 1")? 1 : 0; b += 1; a += ("condition 2")? 1 : 0; b += 1; a += ("condition 3")? 1 : 0; b += 1; a += ("condition 4")? 1 : 0; b += 1; a += ("condition 5")? 1 : 0; b += 1; a += ("condition 6")? 1 : 0; b += 1; // etc etc if(a == b) { //do stuff } 

the whole if should be enclosed in brackets and the or operator is || an not !!, so

if ((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) { ... 

Sometimes you can find tricks to further combine statments.

Like for example:

0 + 0 = 0 

and

"" + 0 = 0 

so

PageCount == 0 PageCount == '' 

can be written like:

PageCount+0 == 0 

In javascript 0 is just as good as false inverting ! it would turn 0 into true

!PageCount+0 

for a grand total of:

if ( Type == 2 && !PageCount+0 ) PageCount = elm.value; 

if((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) { PageCount= document.getElementById('<%=hfPageCount.ClientID %>').value; } 

This could be one of possible solutions, so 'or' is || not !!

Wrap them in an extra pair of parens and you're good to go.

if((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) PageCount= document.getElementById('<%=hfPageCount.ClientID %>').value; } 

OR Operator

if ( con1 == True || con2 == True || con3 == True){ // statement ... } 

AND Operator

if ( con1 == True && con2 == True && con3 == True){ // statement ... } 

Works on mine :D

In case you have to many conditions and you want to add them inside only one conditional statement, then you can add the conditions into an array and then construct the conditional statement like so:

let n = 5 let txt = 'hello' let c = [ n === 5, n === 4, n === 6, txt === 'hello', txt === 'bye' ] if(c[0] || c[1] || c[2] || c[3] || c[4]){ document.write('It satisfies ONE or MORE conditions.'); }else{ document.write('NO conditions have been satisfied.'); }

function go(type, pageCount) { if ((type == 2 && pageCount == 0) || (type == 2 && pageCount == '')) { pageCount = document.getElementById('<%=hfPageCount.ClientID %>').value; } }